This invention relates to imidazopyridine compounds that have urea or thiourea functionality at the 1-position, and to pharmaceutical compositions containing such compounds. A further aspect of this invention relates to the use of these compounds as immunomodulators, for inducing cytokine biosynthesis in animals, and in the treatment of diseases, including viral and neoplastic diseases. The invention also provides methods of making the compounds and intermediates useful in their synthesis.
The first reliable report on the 1H-imidazo[4,5-c]quinoline ring system, Backman et al., J. Org. Chem. 15, 1278-1284 (1950) describes the synthesis of 1-(6-methoxy-8-quinolinyl)-2-methyl-1H-imidazo[4,5-c]quinoline for possible use as an antimalarial agent. Subsequently, syntheses of various substituted 1H-imidazo[4,5-c]quinolines were reported. For example, Jain et al., J. Med. Chem. 11, pp. 87-92 (1968), synthesized the compound 1-[2-(4-piperidyl)ethyl]-1H-imidazo[4,5-c]quinoline as a possible anticonvulsant and cardiovascular agent. Also, Baranov et al., Chem. Abs. 85, 94362 (1976), have reported several 2-oxoimidazo[4,5-c]quinolines, and Berenyi et al., J. Heterocyclic Chem. 18, 1537-1540 (1981), have reported certain 2-oxoirmidazo[4,5-c]quinolines.
Certain 1H-imidazo[4,5-c]quinolin-4-amines and 1- and 2-substituted derivatives thereof were later found to be useful as antiviral agents, bronchodilators and immunomodulators. These are described in, inter alia, U.S. Pat. Nos. 4,689,338; 4,698,348; 4,929,624; 5,037,986; 5,268,376; 5,346,905; and 5,389,640.
Substituted 1H-imidazopyridine-4-amine compounds useful as immune response modifiers are described in U.S. Pat. Nos. 5,446,153; 5,494,916; and 5,644,063. The compounds described in these patents do not have amine containing substitution at the 1-position. Certain 1H-imidazo[4,5-c]quinolin-4-amines that have amide, sulfonamide, and urea functionality at the 1-position are described in PCT Publications WO 00/76505, WO 00/76518 and U.S. Pat. No. 6,331,539. All of the above-mentioned patents and published patent applications are incorporated herein by reference.
Despite these recent discoveries of compounds that are useful as immune response modifiers, there is a continuing need for compounds that have the ability to modulate the immune response, by induction of cytokine biosynthesis or other mechanisms.
We have found a new class of compounds that are useful in inducing cytokine biosynthesis in animals. Accordingly, this invention provides imidazopyridine-4-amine compounds that have urea or thiourea functionality at the 1-position. The compounds which have been found to be useful inducers of cytokine biosynthesis are defined by Formula (I), which is described in more detail infra. Formula (I) is as follows: 
wherein X, Y, Z, R1, R2, R3, R4, and R5 are as defined herein.
The compounds of Formula (I) are useful as immune response modifiers due to their ability to induce cytokine biosynthesis and otherwise modulate the immune response when administered to animals. This makes the compounds useful in the treatment of a variety of conditions such as viral diseases and tumors that are responsive to such changes in the immune response.
The invention further provides pharmaceutical compositions containing the immune response modifying compounds, and methods of inducing cytokine biosynthesis in an animal, treating a viral infection in an animal, and/or treating a neoplastic disease in an animal by administering a compound of Formula (I) to the animal.
In addition, the invention provides methods of synthesizing the compounds of the invention and intermediates useful in the synthesis of these compounds.
As mentioned earlier, we have found that certain compounds induce cytokine biosynthesis and modify the immune response in animals. Such compounds are represented by Formula (I) below: 
wherein
X is alkylene or alkenylene;
Y is xe2x80x94COxe2x80x94 or xe2x80x94CSxe2x80x94;
Z is xe2x80x94NR6xe2x80x94; xe2x80x94NR6xe2x80x94COxe2x80x94; xe2x80x94NR6xe2x80x94SO2xe2x80x94; or xe2x80x94NR7xe2x80x94;
R1 is aryl, heteroaryl, heterocyclyl, alkyl or alkenyl, each of which may be unsubstituted or substituted by one or more substituents independently selected from the group consisting of:
-alkyl;
-alkenyl;
-aryl;
-heteroaryl;
-heterocyclyl;
-substituted cycloalkyl;
-substituted aryl;
-substituted heteroaryl;
substituted heterocyclyl;
xe2x80x94O-alkyl;
xe2x80x94O-(alkyl)0-1-aryl;
xe2x80x94O-(alkyl)0-1-substituted aryl;
xe2x80x94O-(alkyl)0-1-heteroaryl;
xe2x80x94O-(alkyl)0-1-substituted heteroaryl;
xe2x80x94O-(alkyl)0-1-heterocyclyl;
xe2x80x94O-(alkyl)0-1-substituted heterocyclyl;
xe2x80x94COOH;
xe2x80x94COxe2x80x94O-alkyl;
xe2x80x94CO-alkyl;
xe2x80x94S(O)0-2-alkyl;
xe2x80x94S(O)0-2-(alkyl)0-1-aryl;
xe2x80x94S(O)0-2-(alkyl)0-1-substituted aryl;
xe2x80x94S(O)0-2-(alkyl)0-1-heteroaryl;
xe2x80x94S(O)0-2-(alkyl)0-1-substituted heteroaryl;
xe2x80x94S(O)0-2-(alkyl)0-1-heterocyclyl;
xe2x80x94S(O)0-2-(alkyl)0-1-substituted heterocyclyl;
-(alkyl)0-1xe2x80x94N(R6)2;
-(alkyl)0-1xe2x80x94NR6xe2x80x94COxe2x80x94O-alkyl;
-(alkyl)0-1xe2x80x94NR6xe2x80x94CO-alkyl;
-(alkyl)0-1xe2x80x94NR6xe2x80x94CO-aryl;
-(alkyl)0-1xe2x80x94NR6xe2x80x94CO-substituted aryl;
-(alkyl)0-1xe2x80x94NR6xe2x80x94CO-heteroaryl;
-(alkyl)0-1xe2x80x94NR6xe2x80x94CO-substituted heteroaryl;
xe2x80x94P(O)(Oalkyl)2;
xe2x80x94N3;
-halogen;
-haloalkyl;
-haloalkoxy;
xe2x80x94CO-haloalkyl;
xe2x80x94CO-haloalkoxy;
xe2x80x94NO2;
xe2x80x94CN;
xe2x80x94OH;
xe2x80x94SH; and in the case of alkyl, alkenyl, and heterocyclyl, oxo;
R2 is selected from the group consisting of:
-hydrogen;
-alkyl;
-alkenyl;
-aryl;
-substituted aryl;
-heteroaryl;
-substituted heteroaryl;
-alkyl-O-alkyl;
-alkyl-S-alkyl;
-alkyl-O-alyl;
-alkyl-S-aryl:
-alkyl-O-alkenyl;
-alkyl-S-alkenyl; and
-alkyl or alkenyl substituted by one or more substituents selected from the group consisting of:
xe2x80x94OH;
-halogen;
xe2x80x94N(R6)2;
xe2x80x94COxe2x80x94N(R6)2;
xe2x80x94CSxe2x80x94N(R6)2;
xe2x80x94SO2xe2x80x94N(R6)2;
xe2x80x94NR6xe2x80x94COxe2x80x94C1-10 alkyl;
xe2x80x94NR6xe2x80x94CSxe2x80x94C1-10 alkyl;
xe2x80x94NR6xe2x80x94SO2xe2x80x94C1-10 alkyl;
xe2x80x94COxe2x80x94C1-10 alkyl;
xe2x80x94COxe2x80x94Oxe2x80x94C1-10 alkyl;
xe2x80x94N3;
-aryl;
-substituted aryl;
-heteroaryl;
-substituted heteroaryl;
-heterocyclyl;
-substituted heterocyclyl;
xe2x80x94CO-aryl;
xe2x80x94CO-(substituted aryl);
xe2x80x94CO-heteroaryl; and
xe2x80x94CO-(substituted heteroaryl);
R3 and R4 are independently selected from the group consisting of hydrogen, alkyl, alkenyl, halogen, alkoxy, amino, alkylamino, dialkylamino and alkylthio;
R5 is H or C1-10 alkyl, or R5 can join with X to form a ring that contains one or two hetero atoms;
each R6 is independently H or C1-10 alkyl;
R7 is H or C1-10 alkyl which may be interrupted by one or more heteroatoms or when R1 is alkyl, R7 and R1 can join to form a ring;
or a pharmaceutically acceptable salt thereof.
Preparation of the Compounds
Compounds of the invention can be prepared according to Reaction Scheme I where R1, R2, R3, R4, R5, X, Y and Z are as defined above, Bn is benzyl and Rxe2x80x2 is alkyl of one to four carbon atoms, perfluoroalkyl of one to four carbon atoms, phenyl, or phenyl substituted by halogen or alkyl of one to four carbon atoms.
In step (1) of Reaction Scheme I a 3-nitropyridine-2,4-disulfonate of Formula X is reacted with an amine of Formula R1xe2x80x94Zxe2x80x94Yxe2x80x94N(R5)xe2x80x94Xxe2x80x94NH2 to provide a 3-nitro-4-aminopyridine-2-sulfonate of Formula XI. Due to the presence of two sulfonate groups that could in principle be displaced, the reaction may provide a mixture of products that can be readily separated using conventional techniques such as column chromatography. The reaction is preferably carried out by adding the amine to a solution of a compound of Formula X in a suitable solvent such as dichloromethane in the presence of a tertiary amine such as triethylamine. As the sulfonate group is a relatively facile leaving group, the reaction can be run at a reduced temperature (0xc2x0 C.) in order to decrease the amount of undesired 2-aminated and 2,4-diaminated side products. 3-Nitropyridine-2,4-disulfonates are known and can be readily prepared using known synthetic methods, see for example, Lindstom et al., U.S. Pat. No. 5,446,153 and the references cited therein.
In step (2) of Reaction Scheme I a 3-nitro-4-aminopyridine-2-sulfonate of Formula XI is reacted with dibenzylamine to provide a 2-dibenzylamino-3-nitropyridin-4-amine of Formula XII. The reaction is carried out by combining a compound of Formula XI, dibenzylamine, and a tertiary amine such as triethylamine in an inert solvent such as benzene, toluene or xylene and heating the resulting mixture.
In step (3) of Reaction Scheme I the nitro group of a 2-dibenzylamino-3-nitropyridin-4-amine of Formula XII is reduced to an amino group. The reduction is preferably carried out using Ni2B which is generated in situ from sodium borohydride and nickel chloride hydrate in methanol. The reaction is preferably carried out at ambient temperature.
In step (4) of Reaction Scheme I a 2-dibenzylaminopyridine-3,4-diamine of Formula XIII is reacted with a carboxylic acid or an equivalent thereof to provide a 4-dibenzylamino-1H-imidazo[4,5-c]pyridine of Formula XV. Suitable equivalents to carboxylic acid include orthoesters and 1,1-dialkoxyalkyl alkanoates. The carboxylic acid or equivalent is selected such that it will provide the desired R2 substituent in a compound of Formula XV. For example, triethyl orthoformate will provide a compound where R2 is hydrogen and triethyl orthoacetate will provide a compound where R2 is methyl. The reaction can be run in the absence of solvent or in an inert solvent such as toluene. The reaction is run with sufficient heating to drive off any alcohol or water formed as a byproduct of the reaction. Optionally a catlayst such as pyridine hydrochloride can be included.
Alternatively a compound of Formula XV can be prepared in two steps by (a) reacting a diamine of Formula XIII with an acyl halide of formula R2C(O)Cl or R2C(O)Br to provide a compound of Formula XIV and then (b) cyclizing. In step (4a) the acyl halide is added to a solution of the diamine in an inert solvent such as acetonitrile, pyridine or dichloromethane. The reaction can be carried out at ambient temperature. In step (4b) the product of step (4a) is heated in an alcoholic solvent in the presence of a base. Preferably the product of step (4a) is refluxed in ethanol in the presence of an excess of triethylamine or heated with methanolic ammonia. Alternatively step (4b) can be carried out by heating the product of step (4a) in pyridine. If step (4a) was carried out in pyridine, step (4b) can be carried out by heating the reaction mixture after analysis indicates that step (4a) is complete.
In step (5) of Reaction Scheme I a 4-dibenzylamino-1H-imidazo[4,5-c]pyridine of Formula XV is hydrogenolyzed to provide the 4-amino-1H-imidazo[4,5-c]pyridine of Formula I. Preferably the compound of Formula XV is heated in formic acid in the presence of palladium hydroxide on carbon. The product or a pharmaceutically acceptable salt thereof can be isolated using conventional methods. 
Compounds of the invention can be prepared according to Reaction Scheme II where R1, R2, R3, R4, R5 and X are as defined above, Bn is benzyl, BOC is tert-butoxycarbonyl and W is O or S.
In step (I) of Reaction Scheme II the amine protecting groups of a 1H-imidazo[4,5-c]pyridine of Formula XVI are removed to provide a 1H-imidazo[4,5-c]pyridine of Formula II. Preferably a solution of a compound of Formula XVI in a suitable solvent such as dichloromethane is treated with triflic acid at ambient temperature. Compounds of Formula XVI can be prepared using the synthetic method described in Reaction Scheme I. In step (1) a 2,4-disulfonate of Formula X is reacted with an amine of formula BOC-NR5xe2x80x94Xxe2x80x94NH2. Steps 2-4 are then carried out as described above to provide a compound of Formula XVI which is a subgenus of Formula XV.
In step (2a) of Reaction Scheme II, a 1H-imidazo[4,5-c]pyridine of Formula II is reacted with an acid chloride of formula R1xe2x80x94C(O)Cl or an acid anhydride of formula R1xe2x80x94C(O)OC(O)xe2x80x94R1 to provide a 1H-imidazo[4,5-c]pyridin-1-yl amide of Formula XVII. The reaction is preferably carried out by adding the acid chloride or acid anhydride to a solution of a compound of Formula II in a suitable solvent such as dichloromethane or acetonitrile in the presence of a base such as triethylamine. The reaction can be run at a reduced temperature (0xc2x0 C.) or at ambient temperature. The product or a pharmaceutically acceptable salt thereof can be isolated using conventional methods.
In step (2b) of Reaction Scheme II, a 1H-imidazo[4,5-c]pyridine of Formula II is reacted with an isocyanate of formula R1xe2x80x94Nxe2x95x90Cxe2x95x90O or with an isothiocyanate of formula R1xe2x80x94Nxe2x95x90Cxe2x95x90S to provide a 1H-imidazo[4,5-c]pyridin-1-yl urea or thiourea of Formula XVIII which is a subgenus of Formula I. The reaction is preferably carried out by adding the isocyanate or isothiocyanate to a solution of a compound of Formula II in a suitable solvent such as dichloromethane at a reduced temperature (0xc2x0 C.). The product or a pharmaceutically acceptable salt thereof can be isolated using conventional methods.
In step (2c) of Reaction Scheme II, a 1H-imidazo[4,5-c]pyridine of Formula II is reacted with a sulfonyl chloride of formula R1xe2x80x94S(O)2Cl or a sulfonic anhydride of formula R1xe2x80x94S(O)2OS(O)2xe2x80x94R1, to provide a 1H-imidazo[4,5-c]pyridin-1-yl sulfonamide of Formula XIX. The reaction is preferably carried out by adding the sulfonyl chloride or sulfonic anhydride to a solution of a compound of Formula II in a suitable solvent such as dichloromethane in the presence of a base such as triethylamine. The reaction can be run at a reduced temperature (0xc2x0 C.) or at ambient temperature. The product or a pharmaceutically acceptable salt thereof can be isolated using conventional methods. 
Compounds of the invention can be prepared according to Reaction Scheme III where R1, R2, R3, R4, R5, R6 and X, are as defined above.
In step (1) of Reaction Scheme III a 1H-imidazo[4,5-c]pyridine of Formula II is reacted with a sulfamoyl chloride of formula R1xe2x80x94N(R6)S(O)2Cl to provide a 1H-imidazo[4,5-c]pyridin-1-yl sulfamide of Formula XXI. Preferably the sulfamoyl chloride is added to a solution of the compound of Formula II in a suitable solvent such as 1,2-dichloroethane in the presence of a base such as tri ethyl amine. The reaction can be run at an elevated temperature. The product or a pharmaceutically acceptable salt thereof can be isolated using conventional methods.
Alternatively a sulfamide of Formula XXI can be prepared in two steps by (a) reacting a 1H-imidazo[4,5-c]pyridine of Formula II with sulfuryl chloride to generate in situ a sulfamoyl chloride of Formula XX and then (b) reacting the sulfamoyl choride with an amine of formula R1xe2x80x94N(R6)H. In step (1a) the reaction can be carried out by adding a solution of sulfuryl chloride in dichloromethane to a solution of a compound of Formula II in the presence of 1 equivalent of 4-(dimethylamino)pyridine. The reaction is preferably carried out at a reduced temperature (xe2x88x9278xc2x0 C.). Optionally, after the addition is complete the reaction mixture can be allowed to warm to ambient temperature. In step (1b) a solution containing 2 equivalents of R1xe2x80x94N(R6)H and 2 equivalents of triethylamine in dichloromethane is added to the reaction mixture from step (1a). The reaction is preferably carried out at a reduced temperature (xe2x88x9278xc2x0 C.). The product or a pharmaceutically acceptable salt thereof can be isolated using conventional methods. 
Compounds of the invention can be prepared according to Reaction Scheme IV where R1, R2, R3, R4, R5, and X are as defined above and BOC is tert-butoxycarbonyl.
In step (1) of Reaction Scheme IV a 2,4-dihydroxy-3-nitropyridine of Formula XXII is chlorinated using conventional chlorinating agents to provide a 2,4-dichloro-3-nitropyridine of Formula XXIII. Preferably a compound of Formula XXII is combined with phosphorous oxychloride and heated. Many 2,4-dihydroxy-3-nitropyridines of Formula XXII are known and others can be readily prepared using known synthetic methods, see for example, Lindstom et al., U.S. Pat. No. 5,446,153 and the references cited therein.
In step (2) of Reaction Scheme IV a 2,4-dichloro-3-nitropyridine of Formula XXIII is reacted with an amine of formula BOC-NR5xe2x80x94Xxe2x80x94NH2 to provide a 2-chloro-3-nitropyridine of Formula XXIV. The reaction is preferably carried out by adding the amine to a solution of a compound of Formula XXIII in a suitable solvent such as N,N-dimethylformamide in the presence of a tertiary amine such as triethylamine, and optionally heating.
In step (3) of Reaction Scheme IV a 2-chloro-3-nitropyridine of Formula XXIV is reacted with phenol to provide a 3-nitro-2-phenoxypyridine of Formula XXV. Phenol is reacted with sodium hydride in a suitable solvent such as diglyme or tetrahydrofuran to form the phenoxide. The phenoxide is then reacted at ambient temperature, or optionally at an elevated temperature, with a compound of Formula XXIV.
In step (4) of Reaction Scheme IV a 3-nitro-2-phenoxypyridine of Formula XXV is reduced to provide a 3-amino-2-phenoxypyridine of Formula XXVI. Preferably, the reduction is carried out using a conventional heterogeneous hydrogenation catalyst such as platinum on carbon or palladium on carbon. The reaction can conveniently be carried out on a Parr apparatus in a suitable solvent such as isopropyl alcohol, toluene or mixtures thereof.
In step (5) of Reaction Scheme IV a 3-amino-2-phenoxypyridine of Formula XXVI is reacted with a carboxylic acid or an equivalent thereof to provide a 4-phenoxy-1H-imidazo[4,5-c]pyridine of Formula IV. Suitable equivalents to carboxylic acid include orthoesters, and 1,1-dialkoxyalkyl alkanoates. The carboxylic acid or equivalent is selected such that it will provide the desired R2 substituent in a compound of Formula IV. For example, triethyl orthoformate will provide a compound where R2 is hydrogen and trimethyl orthovalerate will provide a compound where R2 is butyl. The reaction can be run in the absence of solvent or in an inert solvent such as toluene. The reaction is run with sufficient heating to drive off any alcohol or water formed as a byproduct of the reaction. Optionally a catalyst such as pyridine hydrochloride can be included.
Alternatively, step (5) can be carried out by (i) reacting a compound of Formula XXVI with an acyl halide of formula R2C(O)Cl or R2C(O)Br and then (ii) cyclizing. In part (i) the acyl halide is added to a solution of a compound of Formula XXV in an inert solvent such as acetonitrile, pyridine or dichloromethane. The reaction can be carried out at ambient temperature. Optionally a catalyst such as pyridine hydrochloride can be included. In part (ii) the product of part (i) is heated in pyridine. If step (i) is run in pyridine, then the two steps can combined into a single step.
In step (6) of Reaction Scheme IV the BOC group is removed from a compound of Formula IV to provide 4-phenoxy-1H-imidazo[4,5-c]pyridine of Formula V. Preferably a solution of a compound of Formula IV in a suitable solvent such as dichloromethane is treated with trifluoroacetic acid or hydrochloric acid at a reduced temperature.
In step (7) of Reaction Scheme IV a 4-phenoxy-1H-imidazo[4,5-c]pyridine of Formula V is converted to a 4-phenoxy-1H-imidazo[4,5-c]pyridin-1-yl sulfonamide of Formula VI using the method of step (2c) of Reaction Scheme II.
In step (8) of Reaction Scheme IV 4-phenoxy-1H-imidazo[4,5-c]pyridin-1-yl sulfonamide of Formula VI is aminated to provide a 4-amino-1H-imidazo[4,5-c]pyridin-1-yl sulfonamide of Formula XIX. The reaction can be carried out by combining a compound of Formula VI with ammonium acetate in a sealed tube and heating (xcx9c150xc2x0 C.). The product or a pharmaceutically acceptable salt thereof can be isolated using conventional methods. 
Compounds of the invention can be prepared according to Reaction Scheme V where R1, R2, R3, R4, R5, and X are as defined above and BOC is tert-butoxycarbonyl.
In step (1) of Reaction Scheme V, a 4-phenoxy-1H-imidazo[4,5-c]pyridine of Formula IV is aminated to provide an N-(4-amino-1H-imidazo[4,5-c]pyridin-1-yl)acetamide of Formula XXVIII, which is a subgenus of Formula I. Preferably a compound of Formula IV is combined with ammonium acetate at an elevated temperature (140-160xc2x0 C.). Optionally, the reaction can be run in a pressure vessel.
In step (2) of Reaction Scheme V, an N-(4-amino-1H-imidazo[4,5-c]pyridin-1-yl)acetamide of Formula XXVIII is hydrolyzed under acidic conditions to provide a 1H-imidazo[4,5-c]pyridin-4-amine of Formula II. Preferably, a compound of Formula XXVIII is combined with aqueous hydrochloric acid/ethanol and heated.
In step (3) of Reaction Scheme V, a 1H-imidazo[4,5-c]pyridin-4-amine of Formula II is converted using conventional methods to a urea or thiourea of Formula I. For example, a compound of Formula II can be reacted with an isocyanate of Formula R1Nxe2x95x90Cxe2x95x90O. The reaction can be carried our by adding the isocyanate to a solution of a compound of Formula II in a suitable solvent such as chloroform, optionally in the presence of a base such as triethylamine, at ambient temperature. Alternatively, a compound of Formula II can be reacted with a isothiocyante of Formula R1Nxe2x95x90Cxe2x95x90S, a sulfonyl isocyante of Formula R1S(O2)Nxe2x95x90Cxe2x95x90O or a carbamoyl chloride of Formula R1R6NC(O)Cl. The product or a pharmaceutically acceptable salt thereof can be isolated using conventional methods. 
The invention also provides novel compounds useful as intermediates in the synthesis of the compounds of Formula I. These intermediates have structural Formulas (II)-(VI) described in more detail below.
One class of intermediate compounds has Formula (II): 
wherein
X is alkylene or alkenylene;
R2 is selected from the group consisting of:
-hydrogen;
-alkyl;
-alkenyl;
-alkyl-O-alkyl;
-alkyl-S-alkyl;
-alkyl-O-aryl;
-alkyl-S-aryl;
-alkyl-O-alkenyl;
-alkyl-S-alkenyl; and
-alkyl or alkenyl substituted by one or more substituents selected from the group consisting of:
xe2x80x94OH;
-halogen;
xe2x80x94N(R6)2;
xe2x80x94COxe2x80x94N(R6)2;
xe2x80x94CSxe2x80x94N(R6)2;
xe2x80x94SO2xe2x80x94N(R6)2;
xe2x80x94NR6xe2x80x94COxe2x80x94C1-10 alkyl;
xe2x80x94NR6xe2x80x94CSxe2x80x94C1-10 alkyl;
xe2x80x94NR6xe2x80x94SO2xe2x80x94C1-10 alkyl;
xe2x80x94COxe2x80x94C1-10 alkyl;
xe2x80x94COxe2x80x94Oxe2x80x94C1-10 alkyl;
xe2x80x94N3;
-aryl;
-heteroaryl;
-heterocyclyl;
xe2x80x94CO-aryl; and
xe2x80x94CO-heteroaryl;
R3 and R4 are independently selected from the group consisting of hydrogen, alkyl, alkenyl, halogen, alkoxy, amino, alkylamino, dialkylamino and alkylthio; and
R5 is H or C1-10 alkyl, or R5 can join with X to form a ring that contains one or two heteroatoms;
each R6 is independently H or C1-10 alkyl; or a pharmaceutically acceptable salt thereof.
Another class of intermediates has the Formula III: 
wherein
Q is NO2 or NH2;
X is alkylene or alkenylene;
R3 and R4 are independently selected from the group consisting of hydrogen, alkyl, alkenyl, halogen, alkoxy, amino, alkylamino, dialkylamino and alkylthio; and
R5 is H or C1-10 alkyl, or R5 can join with X to form a ring that contains one or two hetero atoms; or a pharmaceutically acceptable salt thereof
Another class of intermediates has the Formula (IV): 
wherein
X is alkylene or alkenylene;
R2 is selected from the group consisting of:
-hydrogen;
-alkyl;
-alkenyl;
-alkyl-O-alkyl;
-alkyl-S-alkyl;
-alkyl-O-aryl;
-alkyl-S-aryl;
-alkyl-O-alkenyl;
-alkyl-S-alkenyl; and
-alkyl or alkenyl substituted by one or more substituents selected from the group consisting of:
xe2x80x94OH;
-halogen;
xe2x80x94N(R6)2;
xe2x80x94COxe2x80x94N(R6)2;
xe2x80x94CSxe2x80x94N(R6)2;
xe2x80x94SO2xe2x80x94N(R6)2;
xe2x80x94NR6xe2x80x94COxe2x80x94C1-10 alkyl;
xe2x80x94NR6xe2x80x94CSxe2x80x94C1-10 alkyl;
xe2x80x94NR6xe2x80x94SO2xe2x80x94C1-10 alkyl;
xe2x80x94COxe2x80x94C1-10 alkyl;
xe2x80x94COxe2x80x94Oxe2x80x94C1-10 alkyl;
xe2x80x94N3;
-aryl;
-heteroaryl;
-heterocyclyl;
xe2x80x94CO-aryl; and
xe2x80x94CO-heteroaryl;
R3 and R4 are independently selected from the group consisting of hydrogen, alkyl, alkenyl, halogen, alkoxy, amino, alkylamino, dialkylamino and alkylthio;
R5 is H or C1-10 alkyl, or R5 can join with X to form a ring that contains one or two heteroatoms; and
each R6 is independently H or C1-10 alkyl; or a pharmaceutically acceptable salt thereof.
Another class of intermediates has the Formula (V): 
wherein
X is alkylene or alkenylene;
R2 is selected from the group consisting of:
-hydrogen;
-alkyl;
-alkenyl;
-alkyl-O-alkyl;
-alkyl-S-alkyl;
-alkyl-O-aryl;
-alkyl-S-aryl;
-alkyl-O-alkenyl;
-alkyl-S-alkenyl; and
-alkyl or alkenyl substituted by one or more substituents selected from the group consisting of:
xe2x80x94OH;
-halogen;
xe2x80x94N(R6)2;
xe2x80x94COxe2x80x94N(R6)2;
xe2x80x94CSxe2x80x94N(R6)2;
xe2x80x94SO2xe2x80x94N(R6)2;
xe2x80x94NR6xe2x80x94COxe2x80x94C1-10 alkyl;
xe2x80x94NR6xe2x80x94CSxe2x80x94C1-10 alkyl;
xe2x80x94NR6xe2x80x94SO2xe2x80x94C1-10 alkyl;
xe2x80x94COxe2x80x94C1-10 alkyl;
xe2x80x94COxe2x80x94Oxe2x80x94C1-10 alkyl;
xe2x80x94N3;
-aryl;
-heteroaryl;
-heterocyclyl;
xe2x80x94CO-aryl; and
xe2x80x94CO-heteroaryl;
R3 and R4 are independently selected from the group consisting of hydrogen, alkyl, alkenyl, halogen, alkoxy, amino, alkylamino, dialkylamino and alkylthio; and
R5 is H or C1-10 alkyl, or R5 and X can join to form a ring that contains one or two hetero atoms;
each R6 is independently H or C1-10 alkyl; or a pharmaceutically acceptable salt thereof.
Another class of intermediates has the Formula (VI): 
wherein
X is alkylene or alkenylene;
R1 is aryl, heteroaryl, heterocyclyl, C1-20 alkyl or C2-20 alkenyl, each of which may be unsubstituted or substituted by one or more substituents independently selected from the group consisting of:
-alkyl;
-alkenyl;
-aryl;
-heteroaryl;
-heterocyclyl;
-substituted cycloalkyl;
xe2x80x94O-alkyl;
xe2x80x94O-(alkyl)0-1-aryl;
xe2x80x94O-(alkyl)0-1-heteroaryl;
xe2x80x94O-(alkyl)0-1-heterocyclyl;
xe2x80x94COOH;
xe2x80x94COxe2x80x94O-alkyl;
xe2x80x94CO-alkyl;
xe2x80x94S(O)0-2-alkyl;
xe2x80x94S(O)0-2-(alkyl)0-1-aryl;
xe2x80x94S(O)0-2-(alkyl)0-1-heteroaryl;
xe2x80x94S(O)0-2-(alkyl)0-1-heterocyclyl;
-(alkyl)0-1xe2x80x94N(R6)2;
-(alkyl)0-1xe2x80x94NR6xe2x80x94COxe2x80x94O-alkyl;
-(alkyl)0-1xe2x80x94NR6xe2x80x94CO-alkyl;
-(alkyl)0-1xe2x80x94NR6xe2x80x94CO-aryl;
-(alkyl)0-1xe2x80x94NR6xe2x80x94CO-heteroaryl;
xe2x80x94N3;
-halogen;
-haloalkyl;
-haloalkoxy;
xe2x80x94CO-haloalkyl;
xe2x80x94CO-haloalkoxy;
xe2x80x94NO2;
xe2x80x94CN;
xe2x80x94OH;
xe2x80x94SH; and in the case of alkyl, alkenyl, and heterocyclyl, oxo;
R2 is selected from the group consisting of:
-hydrogen;
-alkyl;
-alkenyl;
-alkyl-O-alkyl;
-alkyl-S-alkyl;
-alkyl-O-aryl;
-alkyl-S-aryl;
-alkyl-O-alkenyl;
-alkyl-S-alkenyl; and
-alkyl or alkenyl substituted by one or more substituents selected from the group consisting of:
xe2x80x94OH;
-halogen;
xe2x80x94N(R6)2;
xe2x80x94COxe2x80x94N(R6)2;
xe2x80x94CSxe2x80x94N(R6)2;
xe2x80x94SO2xe2x80x94N(R6)2;
xe2x80x94NR6xe2x80x94COxe2x80x94C1-10 alkyl;
xe2x80x94NR6xe2x80x94CSxe2x80x94C1-10 alkyl;
xe2x80x94NR6xe2x80x94SO2xe2x80x94C1-10 alkyl;
xe2x80x94COxe2x80x94C1-10 alkyl;
xe2x80x94COxe2x80x94Oxe2x80x94C1-10 alkyl;
xe2x80x94N3;
-aryl;
-heteroaryl;
-heterocyclyl;
xe2x80x94CO-aryl; and
xe2x80x94CO-heteroaryl;
R3 and R4 are independently selected from the group consisting of hydrogen, alkyl, alkenyl, halogen, alkoxy, amino, alkylamino, dialkylamino and alkylthio; and
R5 is H or C1-10 alkyl, or R5 and X can join to form a ring that contains one or two hetero atoms;
each R6 is independently H or C1-10 alkyl; or a pharmaceutically acceptable salt thereof.
As used herein, the terms xe2x80x9calkylxe2x80x9d, xe2x80x9calkenylxe2x80x9d and the prefix xe2x80x9calk-xe2x80x9d are inclusive of both straight chain and branched chain groups and of cyclic groups, i.e. cycloalkyl and cycloalkenyl. Unless otherwise specified, these groups contain from 1 to 20 carbon atoms, with alkenyl groups containing from 2 to 20 carbon atoms. Preferred groups have a total of up to 10 carbon atoms. Cyclic groups can be monocyclic or polycyclic and preferably have from 3 to 10 ring carbon atoms. Exemplary cyclic groups include cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, and adamantyl.
The term xe2x80x9chaloalkylxe2x80x9d is inclusive of groups that are substituted by one or more halogen atoms, including perfluorinated groups. This is also true of groups that include the prefix xe2x80x9chalo-xe2x80x9d. Examples of suitable haloalkyl groups are chloromethyl, trifluoromethyl, and the like.
The term xe2x80x9carylxe2x80x9d as used herein includes carbocyclic aromatic rings or ring systems. Examples of aryl groups include phenyl, naphthyl, biphenyl, fluorenyl and indenyl. The term xe2x80x9cheteroarylxe2x80x9d includes aromatic rings or ring systems that contain at least one ring hetero atom (e.g., O, S, N). Suitable heteroaryl groups include furyl, thienyl, pyridyl, quinolinyl, isoquinolinyl, indolyl, isoindolyl, triazolyl, pyrrolyl, tetrazolyl, imidazolyl, pyrazolyl, oxazolyl, thiazolyl, benzofuranyl, benzothiophenyl, carbazolyl, benzoxazolyl, pyrimidinyl, benzimidazolyl, quinoxalinyl, benzothiazolyl, naphthyridinyl, isoxazolyl, isothiazolyl, purinyl, quinazolinyl, and so on.
xe2x80x9cHeterocyclylxe2x80x9d includes non-aromatic rings or ring systems that contain at least one ring hetero atom (e.g., O, S, N) and includes all of the fully saturated and partially unsaturated derivatives of the above mentioned heteroaryl groups. Exemplary heterocyclic groups include pyrrolidinyl, tetrahydrofuranyl, morpholinyl, thiomorpholinyl, piperidinyl, piperazinyl, thiazolidinyl, isothiazolidinyl, and imidazolidinyl.
The aryl, heteroaryl, and heterocyclyl groups can be unsubstituted or substituted by one or more substituents independently selected from the group consisting of alkyl, alkoxy, methylenedioxy, ethylenedioxy, alkylthio, haloalkyl, haloalkoxy, haloalkylthio, halogen, nitro, hydroxy, mercapto, cyano, carboxy, formyl, aryl, aryloxy, arylthio, arylalkoxy, arylalkylthio, heteroaryl, heteroaryloxy, heteroarylthio, heteroarylalkoxy, heteroarylalkylthio, amino, alkylamino, dialkylamino, heterocyclyl, heterocycloalkyl, alkylcarbonyl, alkenylcarbonyl, alkoxycarbonyl, haloalkylcarbonyl, haloalkoxycarbonyl, alkylthiocarbonyl, arylcarbonyl, heteroarylcarbonyl, aryloxycarbonyl, heteroaryloxycarbonyl, arylthiocarbonyl, heteroarylthiocarbonyl, alkanoyloxy, alkanoylthio, alkanoylamino, arylcarbonyloxy, arylcarbonythio, alkylaminosulfonyl, alkylsulfonyl, arylsulfonyl, heteroarylsulfonyl, aryldiazinyl, alkylsulfonylamino, arylsulfonylamino, arylalkylsulfonylamino, alkylcarbonylamino, alkenylcarbonylamino, arylcarbonylamino, arylalkylcarbonylamino, heteroarylcarbonylamino, heteroarylalkycarbonylamino, alkylsulfonylamino, alkenylsulfonylamino, arylsulfonylamino, arylalkylsulfonylamino, heteroarylsulfonylamino, heteroarylalkylsulfonylamino, alkylaminocarbonylamino, alkenylaminocarbonylamino, arylaminocarbonylamino, arylalkylaminocarbonylamino, heteroarylaminocarbonylamino, heteroarylalkylaminocarbonylamino and, in the case of heterocyclyl, oxo. If other groups are described as being xe2x80x9csubstitutedxe2x80x9d or xe2x80x9coptionally substitutedxe2x80x9d, then those groups can also be substituted by one or more of the above enumerated substituents.
Certain substituents are generally preferred. For example, Y is preferably xe2x80x94COxe2x80x94; Z is preferably xe2x80x94NR6xe2x80x94; and R1 is preferably C1-4 alkyl, aryl, or substituted aryl. Preferred R2 groups include alkyl groups having 1 to 4 carbon atoms (i.e., methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and tert-butyl), methoxyethyl, ethoxymethyl, and cyclopropylmethyl. R3 and R4 are preferably methyl. One or more of these preferred substitutents, if present, can be present in the compounds of the invention in any combination.
The invention is inclusive of the compounds described herein in any of their pharmaceutically acceptable forms, including isomers such as diastereomers and enantiomers, salts, solvates, polymorphs, and the like. In particular, if a compound is optically active, the invention specifically includes each of the compound""s enantiomers as well as racemic mixtures of the enantiomers.
Pharmaceutical Compositions and Biological Activity
Pharmaceutical compositions of the invention contain a therapeutically effective amount of a compound of the invention as described above in combination with a pharmaceutically acceptable carrier.
The term xe2x80x9ca therapeutically effective amountxe2x80x9d means an amount of the compound sufficient to induce a therapeutic effect, such as cytokine induction, antitumor activity, and/or antiviral activity. Although the exact amount of active compound used in a pharmaceutical composition of the invention will vary according to factors known to those of skill in the art, such as the physical and chemical nature of the compound, the nature of the carrier, and the intended dosing regimen, it is anticipated that the compositions of the invention will contain sufficient active ingredient to provide a dose of about 100 ng/kg to about 50 mg/kg, preferably about 10 xcexcg/kg to about 5 mg/kg, of the compound to the subject. Any of the conventional dosage forms may be used, such as tablets, lozenges, parenteral formulations, syrups, creams, ointments, aerosol formulations, transdermal patches, transmucosal patches and the like.
The compounds of the invention can be administered as the single therapeutic agent in the treatment regimen, or the compounds of the invention may be administered in combination with one another or with other active agents, including additional immune response modifiers, antivirals, antibiotics, antibodies, proteins, peptides, oligonucleotides, etc.
The compounds of the invention have been shown to induce the production of certain cytokines in experiments performed according to the tests set forth below. These results indicate that the compounds are useful as immune response modifiers that can modulate the immune response in a number of different ways, rendering them useful in the treatment of a variety of disorders.
Cytokines whose production may be induced by the administration of compounds according to the invention generally include interferon-xcex1 (WFN-xcex1) and/or tumor necrosis factor-xcex1 (TNF-xcex1) as well as certain interleukins (IL). Cytokines whose biosynthesis may be induced by compounds of the invention include IFN-xcex1, TNF-xcex1, IL-1, IL-6, IL-10 and IL-12, and a variety of other cytokines. Among other effects, these and other cytokines can inhibit virus production and tumor cell growth, making the compounds useful in the treatment of viral diseases and tumors. Accordingly, the invention provides a method of inducing cytokine biosynthesis in an animal comprising administering an effective amount of a compound or composition of the invention to the animal.
Certain compounds of the invention have been found to preferentially induce the expression of IFN-xcex1 in a population of hematopoietic cells such as PBMCs (peripheral blood mononuclear cells) containing pDC2 cells (precursor dendritic cell-type 2) without concomitant production of significant levels of inflammatory cytokines.
In addition to the ability to induce the production of cytokines, the compounds of the invention affect other aspects of the innate immune response. For example, natural killer cell activity may be stimulated, an effect that may be due to cytokine induction. The compounds may also activate macrophages, which in turn stimulates secretion of nitric oxide and the production of additional cytokines. Further, the compounds may cause proliferation and differentiation of B-lymphocytes.
Compounds of the invention also have an effect on the acquired immune response. For example, although there is not believed to be any direct effect on T cells or direct induction of T cell cytokines, the production of the T helper type 1 (Th1) cytokine IFN-xcex3 is induced indirectly and the production of the T helper type 2 (Th2) cytokines IL-4, IL-5 and IL-13 are inhibited upon administration of the compounds. This activity means that the compounds are useful in the treatment of diseases where upregulation of the Th1 response and/or downregulation of the Th2 response is desired. In view of the ability of compounds of the invention to inhibit the Th2 immune response, the compounds are expected to be useful in the treatment of atopic diseases, e.g., atopic dermatitis, asthma, allergy, allergic rhinitis; systemic lupus erythematosis; as a vaccine adjuvant; and possibly as a treatment for recurrent fungal diseases and chlamydia.
The immune response modifying effects of the compounds make them useful in the treatment of a wide variety of conditions. Because of their ability to induce the production of cytokines such as IFN-xcex1 and/or TNF-xcex1, the compounds are particularly useful in the treatment of viral diseases and tumors. This immunomodulating activity suggests that compounds of the invention are useful in treating diseases such as, but not limited to, viral diseases including genital warts; common warts; plantar warts; Hepatitis B; Hepatitis C; Herpes Simplex Virus Type I and Type II; molluscum contagiosum; variola, particularly variola major; HIV; CMV; VZV; rhinovirus; adenovirus; coronavirus; influenza; and para-influenza; intraepithelial neoplasias such as cervical intraepithelial neoplasia; human papillomavirus (HPV) and associated neoplasias; fungal diseases, e.g. candida, aspergillus, and cryptococcal meningitis; neoplastic diseases, e.g., basal cell carcinoma, hairy cell leukemia, Kaposi""s sarcoma, renal cell carcinoma, squamous cell carcinoma, myelogenous leukemia, multiple myeloma, melanoma, non-Hodgkin""s lymphoma, cutaneous T-cell lymphoma, and other cancers; parasitic diseases, e.g. pneumocystis carnii, cryptosporidiosis, histoplasmosis, toxoplasmosis, trypanosome infection, and leishmaniasis; and bacterial infections, e.g., tuberculosis, and mycobacterium avium. Additional diseases or conditions that can be treated using the compounds of the invention include actinic keratosis; eczema; eosinophilia; essential thrombocythaemia; leprosy; multiple sclerosis; Ommen""s syndrome; discoid lupus; Bowen""s disease; Bowenoid papulosis; alopecia areata; the inhibition of Keloid formation after surgery and other types of post-surgical scars. In addition, these compounds could enhance or stimulate the healing of wounds, including chronic wounds. The compounds may be useful for treating the opportunistic infections and tumors that occur after suppression of cell mediated immunity in, for example, transplant patients, cancer patients and HIV patients.
An amount of a compound effective to induce cytokine biosynthesis is an amount sufficient to cause one or more cell types, such as monocytes, macrophages, dendritic cells and B-cells to produce an amount of one or more cytokines such as, for example, IFN-xcex1, TNF-xcex1, IL-1, IL-6, IL-10 and IL-12 that is increased over the background level of such cytokines. The precise amount will vary according to factors known in the art but is expected to be a dose of about 100 ng/kg to about 50 mg/kg, preferably about 10 xcexcg/kg to about 5 mg/kg. The invention also provides a method of treating a viral infection in an animal and a method of treating a neoplastic disease in an animal comprising administering an effective amount of a compound or composition of the invention to the animal. An amount effective to treat or inhibit a viral infection is an amount that will cause a reduction in one or more of the manifestations of viral infection, such as viral lesions, viral load, rate of virus production, and mortality as compared to untreated control animals. The precise amount that is effective for such treatment will vary according to factors known in the art but is expected to be a dose of about 100 ng/kg to about 50 mg/kg, preferably about 10 xcexcg/kg to about 5 mg/kg. An amount of a compound effective to treat a neoplastic condition is an amount that will cause a reduction in tumor size or in the number of tumor foci. Again, the precise amount will vary according to factors known in the art but is expected to be a dose of about 100 ng/kg to about 50 mg/kg, preferably about 10 xcexcg/kg to about 5 mg/kg.
The invention is further described by the following examples, which are provided for illustration only and are not intended to be limiting in any way.
In the examples below some of the compounds were purified by preparative high performance liquid chromatography using a Waters Fraction Lynx automated purification system. The prep HPLC fractions were analyzed using a Micromass LC-TOFMS and the appropriate fractions were combined and centrifuge evaporated to provide the trifluoroacetate salt of the desired compound. Column: Phenomenex Luna C18(2), 21.2xc3x9750 mm, 10 micron particle size, 100 xc3x85 pore; flow rate: 25 mL/min.; non-linear gradient elution from 5-95% B in 12 min, then hold at 95% B for 2 min., where A is 0.05% trifluoroacetic acid/water and B is 0.05% trifluoroactic acid/acetonitrile; fraction collection by mass-selective triggering.